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View Full Version : FZJ80 tech - heater not hot


treerootCO
09-08-2008, 08:31 AM
As the cooler mornings have moved in, I have noticed the heater is not hot. I have yet to determine if the engine temp is related and/or the valve isn't working. On hot days with the A/C on for a bit, I can get the gauge to climb and the air coming from the vents is hot. On cool days like this morning, the gauge barely climbs, about 1/8" of an inch up from hot, with the temp gauge mod. Both front and rear heaters seem to blow cold air. I will dig into it at lunch, just looking for the known issues/gotchas that most 80 owners already know about. Thanks in advance.

Uncle Ben
09-08-2008, 08:33 AM
As the cooler mornings have moved in, I have noticed the heater is not hot. I have yet to determine if the engine temp is related and/or the valve isn't working. On hot days with the A/C on for a bit, I can get the gauge to climb and the air coming from the vents is hot. On cool days like this morning, the gauge barely climbs, about 1/8" of an inch up from hot, with the temp gauge mod. Both front and rear heaters seem to blow cold air. I will dig into it at lunch, just looking for the known issues/gotchas that most 80 owners already know about. Thanks in advance.

Since it's both front and rear heaters I would suspect the hot water control valve on the firewall behind the engine.

SteveH
09-08-2008, 09:41 AM
The thermostat would be high on my list of things to check. Either use your hands or a IR thermometer and check the differential between your heater core feed hoses, and check the upper and lower radiator hoses, etc.

Uncle Ben
09-08-2008, 10:52 AM
The thermostat would be high on my list of things to check. Either use your hands or a IR thermometer and check the differential between your heater core feed hoses, and check the upper and lower radiator hoses, etc.

He stated that the engine temps were normal....that pretty much rules out T-stat being the problem.

treerootCO
09-09-2008, 08:39 AM
I suspected the valve, just needed options in case the valve wasn't to blame. Went out this morning and gave her a tug and....POP! Works flawlessly now :thumb:

Uncle Ben
09-09-2008, 09:08 AM
I suspected the valve, just needed options in case the valve wasn't to blame. Went out this morning and gave her a tug and....POP! Works flawlessly now :thumb:

:thumb::thumb:

MDH33
09-09-2008, 10:00 AM
I'm having the same issue with my FJ60. Is there a comparable valve I can check?

wesintl
09-09-2008, 10:03 AM
yes.. it's on the firewall. it's a 3 way connection iirc. A little wire from the control panel moves the valve open or closed.